Electronic motor control apparatus



1949- J. H. BOLLMAN ELECTRONIC MOT OR CONTROL APPARATUS Filed March 28, 1945 kmkmva w l/ENZOR J. H. BOLLMA/V A T TORNE V Patented Aug. 9, 1949 UN] S TAT E S PATENT" OFFICE.

ELECTRONIC MOTOR, CONTROL APPARATUS John H. Bellman,

Rutherford, N. J., assignor to: V

BellTelephone Laboratories,Incorporated, New York, N. Y., a. corporation of Ne'w'Yo'rka ApplicationMarch. 28, 1945;: Serial N022585319 6 Claims. (01. 318-r'30) This invention relates to a motors-control system -and particularly to such: system for rotating ansobject insuch manner as to anticipate the final-position of the rotated object.

In certain known'motorcontrol systems the motor-is utilized by means. of asuitable 'mechanism to:rotate--an-objeot to a certain position. In suohsystems it has beenfound that the motor,

tends to drivetheobject too far because of the inertia .of the mechanism embodying the motor.

This tendsr-to cause the motor-tobeso energized a state of rest. Such-overshootingtends to introducehunting in the-motor .control system whereby undesirable time intervals are introduced in, themotorcontrol system.

The present invention-contemplates such-mo.vementor an obgect that it is driven up to the final position whichit is to occupy. without substantial overshootingn The object of. the invention, is to a provide a motor control system capable of moving an object up toaits final.positionlwithout hunting or overshooting.

The present invention will be disclosed as embodied in an otherwise known type of-motor .con-. trol system andits nature and-mode of operation willbe described after first disclosing the known system. It maybeflstated, however, that the-in.-

vention in'the specific form disclosed comprises an electrical storage circuit fo building up a.-

counter control opposing and eventually nullify-i ing the operating voltage of the motorlsystem. as

thedriven member approaches its'intended stopping point /hereby therdriving powerifor the motor is effectively shut ofi" slightly in advance of a .40 system'to'carry the'driven memberifrom there such stopping point allowing the inertia of .the'

on unto its stopping point.

The present invention will-bereadily understood'from the accompanying drawing which.

shows amotorcontrol system embodying aspecific formof theinvention,

ill

In the drawing a handwheel .llJ is. connected. I

throughgears ll, shaft !2,.difierential gear linkage! l3, and shaft 14 torotorlwincling l8 .of syn.- chro-control transformer l5. Threephase.wind.-v ing, l6 constituting thestatonof the transformer. 15 is connected toa threephase-winding 25 forming the stator of alsynch'ro generatorZS which also includes a rotor winding 21. winding is connectedto the ships'gyro system I! The latter for a purpose that will-he einafter appear. Rotor winding; [.8 is connected to the :input winding of a transformer; l9Wh0seoutput windingis connectedto :the: input circuits of three-element gases tubes: 20, --2 -22 and=;23. A- potentiometen 24 serves to bias the-grids of these tubes;-

The anodes of: =tubes-2i and :2 l are connected.- together throughlthesplit primary winding of ar transformer ;-30;- and the anodes of. tubes, -22 sand 23 are connected i together through: the split pri-i mary :windingof, :atransformer3 1.: Y The secondsystem-11 The :output -winding 0f transformer 33 is con: nectedto winding 35 of. aspinnermotor- 36 which n is joinedbyshaft3l, gears 38,.s'haft 39,Vgear linke age .|3, and shaft v H'l to-ibrushes M of a commutatortransmitter A2. I'hese brushes comprise three in number, eachlbeing spaced degrees from the others. Thistransmitterincludes a core 43 .v embodying aaprimary winding connectedby'. leadsAS to the alternating currentjsource32, and a secondary "winding 46 'with'which the arms 4| Three concentric are in slidabler engagement. rings 41 each of which'is associated withone of the'three brushes 4! are-connected to the threeph'ase"winding'oftraining motor 45 which embodies a single phase Winding'49 c'onnected'by leads 50-"tothe alternating 'current source 32;

A sh'aft'il joined 'toboth the training motor-48" and projector -52r otates the latter-in clockwiseor counter-clockwisedirections in a manner that will b'e presently explained? In" the operation of the circuit'portion above described-the potentiometer is adiusted to bias the' griclsofrthe tubes-2ils H522 and-23 and thereby prevent the'se tubes from firing in the absence offian input voltage -fromithe transformer" l9.

This? indicatesfa: balanced'ielectrical condition in the-transformer. 15;: that is, suchrelation of the position: =ofrithel'trotora winding l 8 with :reference to 'the stator windings I6--that :the magnetic field: eifective in the transformer 15 induces no voltage iniheJotor -Winding 18.x Ina this connection it will -:.be-:und'erst00d that-the -voltage for" exciting; 7 the transformerd 5- is:--ob.tained from thetships gyro isystemin'the circuit previously :traced;

Electrical unbalance is establishedin the transformer. l5.,-by ..(1).la changerin the magnitude of the three-phase voltage (effectively suppliedby r 22 will fire. 32 is connected to the ships gyro system H, the

3 stator windings 25 to stator windings I6, and (2) rotation of the rotor winding is by an actuation of the handwheel H]. In connection with (1). the magnitude of the voltage induced in the stator windings 25 and supplied to the stator windings I6 is determined by the amount of the rotation of the rotor winding 21 relative to its associated stator windings 25. The amount and duration of such rotation, clockwise or counterclockwise, of the rotor winding 21 depends'on the change of the ships course either to the port or starboard direction. Hence, the effective magnitude of the voltage supplied by the stator windings 25 to the stator windings |6 depends on the change in the ships course. This voltage introduces an unbalanced condition in the transformer l5. In connection with (2), the unbalance is established when, with nochange in the magnitude of the voltage supplied to the stator windings l6 as described above under (1) the rotation of handwheel Ill causes actuation of shafts l2 and I4 and gear linkage I3 and thereby rotation of the rotor winding I8. This introduces an unbalanced condition in the transformer l5. Due to suitable differential gearing in the gear linkage l3, rotation of handwheel i actuates the rotor winding l8 but does not afiect the position of the brushes 4| on the commutator transmitter 42.

When the unbalanced condition is introduced in the transformer 5 by either (1) or (2) above, 1

motor winding from the alternating current source 32 in a manner to be explained hereinafter. The constants of the input circuits of these tubes are so chosen that the latter fire with approximately one-half degree displacement of the rotor windings l8 and 21 with reference to that position at which the respective transformers l5 and 26 would be balanced in an electrical sense.

The anode circuits of tubes 20, 2|, 22 and 23 are supplied through the transformers 3t and 3| with an alternating voltage of approximately 225 volts from the source 32. These tubes are so arranged in circuit that they fire only when their grid and anode voltages are in phase. Hence, for one direction of rotation of either rotor winding |8 or rotor winding 2'l, and therefore for a given phase of the voltage applied to their grids, only tubes 2|] and 23 will fire; and for the opposite direction of rotation of either rotor winding l8 or rotor winding 21, and therefore for a HBO-degree change in phase for the voltage applied to their grids, only tubes 2| and As the alternating current source proper phasing of the voltages in the input and output circuits of the tubes 20, 2|, 22 and 23 is effected.

When the tubes 20 and 23 are fired, a voltage of 225 volts and given phase is applied through transformer 33 to the winding 35 of motor 38 whereby the latter is caused to rotate in a given direction. When'the tubes 2| and 22 are fired, a voltage of 225 volts and 180-degree change of phase is supplied through transformer 33 to the 4 winding 35 of motor 36 causing the latter to rotate in the opposite direction.

Rotation of the motor 36 effects rotation of shaft 37, gears 38, shaft 39, gear linkage l3 and shaft 48 and thereby rotation of the brushes 4| on commutator transmitter 42. The relative geometrical positions of the three brushes 4| with reference to the mid-turn of secondary winding it determines the magnitude and phase relationship of the three-phase voltage supplied to the three-phase winding of the training motor 48. The interaction of the magnetic fields due to the voltages efiective in such threephase and single phase windings produces a torque whose direction and magnitude depend on the relative magnitude and phase of the voltages in the respective windings. This torque effects rotation of the shaft 5| and thereby the projector 52 in either clockwise or counter-clockwise directions.

As the projector 52 is being rotated in the foregoing manner, the motor 36 also efiects rotation of the shaft Hi and rotor winding l8 attached thereto. This rotation is such that it tends to restore electrical balance in the transformer l5 whereupon the induction of a voltage in the rotor winding H3 is substantially terminated. Consequently, the pair of tubes 20 and 23, or 2| and 22 cease firing and thereby cause discontinuance of the voltage to the winding 35.

The gearing is so arranged that one rotation of hand-wheel Ill effects approximately 5 degrees rotation of the projector 52; and that whatever change is made in the position of the ships bearing with respect to true north, the projector 52 is caused to rotate a suificient amount in the proper direction to maintain the projector 52 in true bearing and at the same time electrical balance is caused to be reestablished in the transformer I5. For example, if the ships position is changed 10 degrees to port or starboard with respect to true north, the projector 52 is rotated a suflicient amount in the proper direction to a position corresponding to that of the ship with reference to true north, and the rotor winding I8 is rotated 10 degrees from its original position in order to reestablish electrical balance in the transformer |5.

In accordance with the present invention, a resistor 60 and capacitor 6| are connected in parallel such that one common terminal 62 is joined by lead 63 to lead 64 which is common to the cathodes of the tubes 20, 2|, 22 and 23; and such that a second common terminal 65 is connected to ground 66.

In the operation of the invention, the firing of tubes 20 and 23, or 2| and 22 causes the capacitor 6| to obtain a charge in the circuit including ground 34, primary winding of transformer 33, windings of transformers 3|] and 3| connected to the anodes of tubes 20, 2|, 22 and 23, anode-cathode circuits of the fired tubes, common cathode lead 64, lead 63, capacitor 6| and ground 66. The charge on capacitor 6| supplies an additional bias to the grids of the fired tubes to cause them to cease firing when the rotor Winding I8 is approximately 3 degrees away from that position at which the transformer |5 would have electrical balance restored thereto. Thereafter, the inertia of the mechanical system causes the rotor winding l8 to coast to the balanced position without huntin or substantial overshooting.

To take one illustration; For a rotation of the motor winding I8 approximately up to 3 degrees ".i in' efthetfdirectiominirespo se tofaislmlravchangee mototf said tubes being norrnally blasd to th' in the ships courseior an-actuationbt thefshmd non-fired Gond'itiom mans fofi supplyin san cp- WhBSF"! W31=Heflihbff mentionem ZVOIUQIQ'GFF" mating-voltages f varying 'magh'itud -and Sig purse of 'prope'x p'hesefiis in tosaid'controlli g mans tofire preselected tube grids 5 -whereby said controlling mean's iscausedto com-' eit 1e tnbesrie and fi l fi nect said source to'saidrnotor rnean's and'to app] enal-m :om themomritw of this voltalger' This the volt'age'o'f said 'source with a certain polarity commencesthe'plaeement ot a charge omcapafi to said-motonmeans to effect therotation of said i itor flfi and atr the samewtim'e the application obfi'ect ina predetermined direction-,said suppliof I spurt of voltaige to' rrlotor"winding ifif This ing n'iean's including a rotor actuatd'by'said ni Y charge biases the control grids of the fired tubes' toz*-"n1ear'1's'" to a"positionat which no 'oper'ati whereupon the'y are cause'to ceasefiringand voltage-is supplied to said controlling means-"and therebfiterminate voltage spiirt." This volt at wh'ichsaid controllingmeanseffectively'dis'con= sum'cient to enable-the nects'-saidso1irce 'fromsaid motor "means, and motor36 tb -actizate therotor winding: "3 tome inertialess means operated by "said controlling b.2iit'ti10dpositiinl Consequentlyi'asecondiiolt means 'duri'ng the firingof said preselected tubes age puIseof the-same phaseis Fappli'ed to =:the- I for augmenting 'the normal bias on said tubes to grlds of bes=caus1n g-the"-sanie*pair'to are res "said'-preselected tubesto the non-fired again? On more cap'aci'tor 'li'l cornrrm'encesto" con itio'n- "and thereby, causing said controlling take' oma 'charge, an a spurtof Voltage-is started izo meansto effectively disconnect said "sourcefroin j tothe 'motor windin '3'5. Th'chargebiasesth'esaifimotor"when-said rotor is a predetermined control- 'grids' of the fired tubesf "causing "them" anguiaf dista 'nce'from its no-voltage position, the to"ceasefiriiigandtherebyterminate th voltage inertia of "said- "system thereafter causing said spurt?This*voltagespurt-niayjalso beinsuflicient rotorto 'coastthiough the'predetermineddistance to enabl 'mdtoiGS toretnrn the"rotor-wind- -to its no-voltage position Without substantial ing t8 t'o balanced-"position: Accordinglyjthe overshooting; intermittent"tubefiringandvoltage-"spurts 'are 2." A controlsystem' according'jto claim" lin continued andthereby"tlie"motor'36 is caused to which saidlinertialess means inclndes'a capaci'tof="" rotate t-he roton windi'rig HI "in "small stages .until' connected to said controlling means 'for receiving" the balanced position oif-"trar'is'formerl5 i's"'at- "a charge.therefrom'during the time interval when tafndf Denn s the periods when :the tubes are said presel'ecteditubes are fired and" said con-' not 'firin'g, 'the"charg'e on"capacitor 6l"leaks"ofi" trollin mean's effectively connects said source'to throu'gh resi'storfin to ground 66* soth'at"the* said mot'orfandithe voltage of'the charge on said magnitnde "of theWmta ee"impr d 0n" h 0 fi or ements the normal bias on said til e ll trohg'rids"ofthe'tubes"is"adequate'to causeon'e 'tdrestore'said 'preseiecte'd tubesto theno'n fired pairoftubg td fifg condition and thereby causes "said controlling Tdtake 'a"sec'onddllustrationr Fdfr'a 'rota tio nrof m n c f v y id rce fr m therotor windingflafbeyonwadegreesdn either" i mo or' wherr' id' ro r" ta ns dpr directioninwespon'se to a similar "change in'the terminedangulardistance withreferencetosaidshlpscourse :01-an a'ctnati'onof the handwhe'el" l u no-voltage position: as previously-"pointed? outyn voltage pulseof 5A 0nt 1syst m di t la m 1 in proper"'phaseapplied'totubes"20,"2If '22 andzl' whichsaid'. controlling means comprises'a-plu-f causes?one painioffthem to lonize as'previongly' ralit'y of gaseous discharge tubes "each including pointedhutan'dther'ebyjcauseavoltage spurtto" a control g l' Cathode and eg' i besup'pli'ed "toth'e' m'otor""win'difig35funtil the meansfor'connecting said anodes, cathodes and motor"'36attainsrfdll"speed. At "the" same-time" sourcein circuit, other circuit means forconnectth iacemenrore; c'harge'nnc'apacitor'61 55mm 1 ngisa d t grids nd supp yi g ans in mencedi' Botli the"application" f the*"vo1ta e" circuit, certain of said'tubes'firingwhen the'volt-- gpuflrto t e, ng g--fandthec'placenienfiof ages"efiectivein"thei1'-'cont1'ol grid and'theiram thetcharge "oni th'e capacitor 6 Fcontlm'iemntn 'Odc'an'd cathodecircuits have one'sign and others them'oto'r '35T'has returnedt'herotorlwinding"l8"' of said tubes firing When the voltages effective in approximatelywitnimrs"degrees"*of'itsbamnced'f thei'ncontrol glidand their anode and cathode" position." At"thispoint ithelcharge' onicapaci'toii circuits have the oppos e" S Said ce a ntu f El 'sb'biases'thdnred tubessthat'they cease'firin'g" s pplying a voltage of one pol ritydrom said toi'termina te the voltag e'spurt to the-motor wind: 'source' to said motor-' to efiect its rotation' in a ingiflfli. Alt-houghir t charge on? capacitorf'fi l' given direction and-said other tubes supplylng 'a leaks'off'thr'oughresistor1il)togroundtifidurin'g'fv voltage of opposite' polarity fromsaid source to thenomfirin'g periods*of'thtnbith chargre: said rnotor to "effect its' rotation in an opposite mainingion'thecapacitof6I*issufllcienVtb predirection" said motor actuating said "rotor'-in op-- vent tnetubes fromfirin'g' inresponse to the'voltor posite' rotary i s to -v e p siti n; age -applied"to"their control grids due 'tothe un anitsaid-ihrtialess means includes an-Rg-efinetbalanced conditionfofrthe "transfor'merdi; once" Work, Tnrther circuit meansto connect" -'fir T the rotorwindihg'lfigets"within 3 degrees of its terminal ot said netwo1-k"to"'said cathodes,'-and balanced position.=Thereafl3eh-the' inertia of the additional 'circ'uit me'a-ns for con c mechanical system causes the rotor winding 18 e 'f' d fi f0 e f e t p o' to return more balarieed nos'i-tion withbiit hunt of 'said network taking' on a charge 'during the ing or excessive overrunning. firingbf either said "certain or other'=tubes;' the"" t is claimedtis-mvoltage 'of thechargeon'thecapacitor au'gment 1. A motor control system comprising an obingthe 'nor-n'lal bias on the contlol grlds of said: ject adapted for rotation, meansincluding a mo 'TH tubes thre Callsifigithc sp five' certa'lnrorf tonfor rotating said'object', a sourceof electrical othertnbes toceasf firirig' when saiti rotor hasr voltage,means including-aplurality of gaseous" attained the predetermined angular distanoe' discharge tubes for'controlling' theefiective =con-- from its'no voltg position? nectio'n *of lsaid" sonrc'wto"'said rnotor and--the-'* A inot'or control-system comprisnrg' an ob-"-"= efiective'"dis'connection of"sald'sburce from-sam iww p d for rct i'ommeans in l d e a mus 7 torfor rotating said object, a source of alternating voltage, means including a plurality of gaseous discharge tubes for controlling the effective connection-of said source to said motor and the effective disconnection of said source from said motor, said tubes bein normally biased to the deionized condition to disconnect said source from said motor means, means for supplying an operating voltage of varying magnitude and sign to said controlling means whereby said last mentioned means is caused to ionize preselected tubes to connect said source to said motor means with predetermined voltage signs and predetermined time durations, said supplying means including a rotor movable by said motor means to a position at which said supplying means is caused to supply no operating voltage to said controlling means, said last mentioned means being caused by the no-voltage position of said rotor to maintain said preselected tubes to the deionized state and thereby to disconnect said source from said motor, and inertialess means including a storage circuit for electrical energy, said circuit taking on a charge of electrical energy when said controlling means is caused to ionize said preselected tubes to connect said source to' said motor, said controlling means beingso responsive to the voltage of said circuit as to increase the normal bias on said tubes whereby said preselected tubes are deionized to disconnect said source from said motor when said rotor has been moved to a further position lying a predetermined distance in advance of the no-voltage position, the inertia of said system thereafter moving said rotor from said further position to the no-voltage position without substantial overshooting.

5. In an object rotating system, means for rotating said object, a source of alternating voltage, a plurality of gaseous discharge devices, each in-- cluding a control grid, a cathode and an anode, for connecting the voltage of said source to said rotating means with different signs, said control grids being normally biased to establish the deionized condition therein and thereby to disconnect said source from said rotating means, means for supplying to said control grids a voltage having a predetermined magnitude in response to an action of preselected amount and having a sign indicative of the direction of said action, said supplying means having a condition at which no voltage is supplied to said control grids, means for connecting said source, anodes, rotating means and supplying means in circuit so that certain devices ionize when the voltages applied concurrently to their control grids and anodes have one sign and. so that other devices ionize when the voltages applied concurrently to their control grids and anodes have the opposite sign, means capable ofv movement to a position at which the no-voltage condition is established in said supplying means, said rotating means being responsive to the ionization of said certain or other devices to rotate said object to an amount proportional to the preselected amount of said action andv in a direction corresponding to the direction of said action, said rotatin means simultaneously with the rotation of said object also moving said movable means to establish the novoltage condition in said supplying means, and means compensating for the inertia of said system, comprising a capacitor and a resistive means connected to said cathodes of said devices, said capacitor being charged when said certain or other devices are ionized, the voltage of the charge on said capacitor supplying additional voltage position, thereafter the inertia of said,

system moving said movable means through the predetermined distance to the no-voltage position without substantial overshooting, said resistive means dissipating the charge on said ca- 1 pacitor when all said devices are in the deionized condition.

6. In combination with a system for rotating an object comprising means for'rotating said object, a source of alternating voltage, means including a plurality of gaseous discharge tubes operable in response to a further voltage for applying the voltage of said source with difierent signs to said rotating means, said operable means being normally biased to the unoperated condition so as to maintain said tubes deionized and thereby to withhold the voltage of said source from said rotating means, means for supplying the further voltage with a predetermined magnitude and sign to said operable means for ionizing preselected tubes thereby operating said last mentioned means in response to an action of a preselected amount and direction in such manner that the predetermined magnitude of the further voltage is proportional to the preselected amount of said action and in such manner that the predetermined sign of the further voltage is indicative of the preselected direction of said action, means capable of movement to a position at which said further voltage means terminates the further voltage, means for connecting said source, rotating means, operable means and further voltage means in circuit, said rotating means rotating said object to an amount and direction corresponding to the preselected amount and direction, respectively, of said action in response to the voltage of said source as controlled by said operable means, said rotating means simultaneously with the rotation of said object also moving said movable means until said further voltage means terminates the further voltage supplied to said operable means, and means compensating for the inertia of said system to prevent substantial overshooting of said movable means, comprising means for storing electrical energy when said preselected tubes are ionized and said operable means is applying the voltage of said source to said rotating means, the voltage of the stored energy augmenting the normal bias on said operable means thereby causing said operable means to return to the unoperated condition by deionizing said preselected tubes when said movable means has been moved to av furtherv position lying a predetermined distance in advance of the first-mentioned position, thereafter the inertia of said system moving said movable means from said further position to the first-mentioned position without substantia overshooting.

JOHN H. BOLLMAN.

REFERENCES CITED The following references are of record file of this patent:

UNITED STATES PATENTS in the 

